Will Blurty be requiring a birth year to get an account? Many free users I've encountered are clearly underage (talking about high school, etc.) but because they don't list their age or birth year, they can't be reported.
I know there are a lot of 18 year old seniors (I unfortunetly, was not one of them) but there are very, very few 18 year old freshmen-juniors. And if the people I found were seniors, I have lost a lot of faith in the American school system. ^_^